Manufacture of air bags

ABSTRACT

Tubular plastics film ( 18 ) is bunched up. Air is blown through one end of the tube by a fan ( 64 ). The air passes through the tube and through a spreader ( 30 ) of the film and then past a sealing station. The sealing station effects two adjacent seals across the film and also creates a line of weakness between those adjacent seals in a single operation. Air bags are formed between spaced seals effected in sequential sealing operations.

The present invention relates to air bag manufacturing apparatus, amethod of manufacturing air bags and a cartridge arranged, in use, to bemade into air bags.

In a known machine for forming plastics bags with air in them such asdescribed in our co-pending European application 02 251 571.2 publishedunder number 1 245 491, the contents of which are hereby incorporated, anozzle pierces and injects air into a tube of film. Whilst this providesvery satisfactory bags there are some drawbacks. In particular, thepenetration of the nozzle into the tube requires a considerable amountof machinery which is expensive to supply and requires regularmaintenance. Furthermore, the length of each bag is not readilyadjustable.

Other methods of forming air bags comprise having a sheet of plasticsfolded about its length to present a fold at one side and open edges atthe other. The sheet is pre welded across its length at spaced locationsthat correspond to the length of the bag. Air is blown in from the sideand the side is subsequently sealed to form the bag. This film isexpensive. Furthermore, the sides of the bag do not always opensatisfactorily thus producing bags with inconsistent air fillings. Inaddition, the length of each bag is predetermined by the partlypre-sealed film.

It is an object of the present invention to attempt to overcome at leastone of the above or other disadvantages.

According to one aspect of the present invention air bag manufacturingapparatus comprises a tube of film arranged to be fed to a sealingstation which station, in use, is arranged to apply seals across thewidth of a tube to trap air in the tube between two spaced seals, theapparatus being characterised in that air is supplied to be trappedbetween two spaced seals through the tube, from an open end of the tube.

The tube may be supplied to the sealing station from a supply station.

The supply station may be arranged to maintain a passage through thetube. The supply station may include a hollow member such as a tubularmember around which the tube is located. The air that is arranged to betrapped between two spaced seals may be arranged to pass through theinterior of the hollow member or, alternatively or additionally, throughthe interior of the tube over the exposed interior wall of the tube, forinstance by the tube having nothing in it along its bunched up length.

The tube may be located in a container of the supply station. The tubemay be detached from the container around the sides of the tube oraround the ends of the tube or both.

The container may include an outlet through which film is fed to thesealing station.

The tube of film may be arranged to be bunched up, such as by beingbunched up in the axial extent of the tube. Prior to any air bags beingmade from the tube, that bunching up may comprise the ratio of thelength of bunched up tube to the length of the tube when stretched outbeing more than 1:2 or more than 1:10 or in the region of 1:100 or morethan 1:100 or in the region of 1:200 or more than 1:200 or in the regionof 1:300 or more than 1:300. The bunched up tube may be arranged tomaintain an opening throughout its length such as by maintaining such anopening solely as a result of compression induced during bunching of thetube.

The supply station may be removably mounted on the apparatus. Adifferent supply station can be used when a previous supply station isno longer required, for instance because the previous supply station isempty.

During mounting of the supply station, the supply station may bearranged to partially engage with the apparatus and move in at least oneaxial direction with respect to the elongate axis of the tube andpreferably in two axial directions when so engaged, either or both ofwhich axial directions of movement may be against a resilient bias orwith a resilient bias with for instance, movement in one axial directionbeing against the resilient bias and movement in the other axialdirection being with the resilient bias. The resilient bias may comprisea spring such as a compression spring.

The supply station may be arranged to be held in position by theapparatus when mounted thereon to prevent further movement of the supplystation towards the sealing station. The supply station may be arrangedto be at least partially supported at at least one end, for instance theend furthest away from the sealing station, by, for instance, a supportmember of the apparatus extending within the supply station, which mayalso extend along the supply station. Alternatively or additionally, thesupply station may be arranged to be at least partially supported at oneend, preferably the end nearest the sealing station, by a brush or anupper and lower brush. Alternatively or additionally, the supply stationmay be supported from beneath the station such as, for example, restingon one or more spaced supports.

The supply station may comprise an end stop for at least one end, andpreferably-both ends, which end stops are arranged to resist the passageof film over one or each stop without assistance. The or each end stopmay comprise a flange such as a circular flange extending radiallyoutwardly with respect to the longitudinal axis of the tube at that end.

The tube of film may be arranged to pass over a spreader having agreater extent in the direction across the tube in the direction that aseal made by the sealing station is arranged to make than in a directiontransverse thereto. The spreader may be hollow and may be arranged tohave air passed through the spreader which air is the air that isarranged to be trapped between two spaced seals. Alternatively oradditionally air may be arranged to flow over at least one andpreferably two surfaces, which may be opposed surfaces, when air isbeing supplied to the tube.

The spreader may be located downstream of the supply station. Thespreader may be fast with the supply station. The spreader may bedetachably mounted on the supply station such as by means of a force fitor a bayonet fit with the supply station. Alternatively or additionally,the spreader may be loosely held within the film.

The apparatus may include drive means arranged to supply film to thesealing station. Alternatively or additionally, the film may be arrangedto be manually drawn through the sealing station.

The apparatus may be arranged to impart a differential force on a tubeupstream of the sealing station which is arranged to urge axially spacedportions of the tube apart from each other. The differential force maybe arranged to be applied by a pair of members which may be spaced fromeach other. The downstream one of these pair of members may be arrangedto drive the tube, for instance from opposed sides of the tube. Theupstream member may also be arranged to exert a drive to the film withthe speed of drive imparted to the tube by the upstream drive memberbeing less than the speed of drive imparted by the downstream member.Slippage of the film may be arranged to occur between the upstreammember and the downstream member. When either or both of the members aredriven they may comprise rollers.

The sealing station may be arranged to effect a seal when the tube isstationary or when the tube is moving. The sealing station may bearranged to apply heat to effect a seal and then hold the tube at thesealing station, for instance for a predetermined period of time whilstthe temperature induced by the heat decreases, before allowing the tubeto advance.

The sealing station may include a seal actuator such as anelectronically activated actuator arranged to cause the film to be movedagainst sealing means. The actuator may be arranged to hold the filmagainst sealing means. The actuator may be arranged to cause the film tobe held against the sealing means after the force effected by theactuator is no longer being applied such as by a linkage being caused tomove over centre upon activation of the actuator. The film may be causedto be held against sealing means against a resilient bias. The sealingstation may include a release actuator such as an electronicallyactivated actuator arranged to release a hold on the film againstsealing means. The release actuator may be arranged to move a linkagethat is over centre back over the centre. Where a seal actuator and arelease actuator are provided these may be arranged, upon actuation, tomove in opposed directions which may be transverse or perpendicular tothe direction of movement caused to seal or release the film from thesealing means. The seal actuator and the release actuator may beconnected to a linkage such as a pivotal linkage which linkage mayinclude a lost motion effect which lost motion effect may also include apivot.

The sealing station may be manually actuatable or automaticallyactuatable or both. The sealing station may be arranged to form a pairof adjacent seals during each sealing operation. The sealing station maybe arranged to effect a weakening of the tube between adjacent sealswhen effecting a sealing operation, for instance by exerting a series ofperforations across the tube when effecting the seal.

In use, bags may be arranged to be pulled at a location downstream ofthe sealing station, for instance by being pulled manually orautomatically for instance by a pair of rollers.

The frequency of the operation of the sealing station may be adjustableor, alternatively or additionally, the rate of feed of the tube past thesealing station may be adjustable.

The air that is arranged to be trapped between two spaced sides of thetube may be supplied by a fan which may, for instance, be supplied tothe upstream end of the tube such as through an opening in a containerof the film.

According to another aspect of the present invention a method of formingbags containing air comprises supplying air to a tube from one end ofthe tube, through the tube, and past a sealing station and effecting aseal across the tube by the sealing station.

The method may comprise supplying air through the tube in flowcommunication with the interior wall of the tube.

The method may comprise passing the air through the tube with the tubehaving been bunched up such that the tube maintains a clear openingthrough the tube under its natural flexure.

The method may comprise drawing film off a bunched up supply of film andmoving that film to the sealing station.

The method may comprise replacing a supply of film with a differentsupply of film, for instance when the previous supply of film is emptyor is no longer required. The method may comprise replacing a supply offilm by supplying a container housing film and the method may compriselocating the container down onto an upwardly facing support or supports.

The method may comprise causing the film to pass over a spreader havinga greater extent in the direction across the tube in the direction thata seal is made than in a direction transverse thereto. The method maycomprise passing the film over the spreader when loading the machinewith film or causing the film to repeatedly be drawn over the spreaderduring manufacture of the bags. The method may comprise passing airthrough or around or over the spreader with the air subsequently beingtrapped between two spaced seals.

The method may comprise attaching the spreader to a supply station priorto making the bags. Alternatively or additionally, the method maycomprise supporting the spreader with the film.

The method may comprise straightening the length of film at a locationdownstream from where the film is bunched up, for instance by exerting atension force on the film.

The method may comprise manually actuating the sealing station to causea seal to be made or automatically actuating the sealing station tocause a seal to be made or both.

The method may comprise supporting the supply of film by a member thatresists both a downwards and a moment force caused by the weight of thesupply of the tube or, alternatively, supporting the supply of filmwithout a moment force having to be exerted on the supply of film.

The method may comprise pulling bags off the machine from a locationdownstream of the sealing station. Alternatively or additionally, themethod may comprise the air being supplied through the tube urging thefilm past the supply station which air may comprise the sole forceurging the tube forwards.

The method may comprise varying the frequency of operation of thesealing station or varying the speed of supply of the film or both. Themethod may comprise automatically making bags of a first length from thesupply of films and then adjusting the machine to make bags of adifferent length or to make bags having a different content of air orany combination thereof. The method may comprise varying the length ofthe bag by varying the length of film between seals such as by manuallypulling the required length before effecting the seal.

The method may comprise varying the amount of air in a given length ofbag, for instance by varying the direction that the tube leaves thesealing station or restricting the expansion of the walls of the tubedownstream of the sealing station such as manually making thatrestriction or by varying the speed that the film passes the sealingstation or any combination thereof.

The method may comprise a packer making a bag of a first length having afirst volume of air, making a bag of the first length having a secondvolume of air, making a bag of a second length having a third volume ofair which third volume may be the same as the first or second volumes orany combination thereof.

The method may comprise supplying air through the tube from a fan.

The present invention also includes a method of making bags when usingapparatus as herein referred to.

According to a further aspect of the present invention a film cartridgearranged, in use, to be made into air bags, comprises an elongate tubewhich tube has been bunched along its elongate axis such that the lengthof the bunched up film is less than the length of the extended film, thefilm including a passage through the length thereof through which, inuse, air is arranged to pass in order to comprise air in the air bagsfrom the tube of film.

The degree of bunching of the film may be such that the ratio of thebunched length of the tube to the fully extended length of the tube maybe greater than 1:2 or greater than 1:10 or in the region of 1:100 ormore than 1:100 or in the region of 1:200 or more than 1:200 or in theregion of 1:300 or more than 1:300.

The passageway may be open even when air is not passing through thefilm. The passage may be arranged to be open through the natural flexureof the bunched up film. The cartridge may include a container withinwhich the film is located. The film may be detached from the containeraround the side of the film or around one or both ends or anycombination thereof.

The cartridge may include an elongate member extending through the tubethrough which member air is arranged to flow. The elongate member maycomprise a carrier.

The cartridge or carrier or container may include a stop at at least oneend arranged to inhibit the passage of the tube off that end. The stopmay be integral with the carrier. The stop may comprise a disc.Alternatively or additionally, the cartridge may be arranged to besupported from beneath without any moment having to be exerted on thecartridge to effect the support.

The carrier may comprise a hollow member such as a tubular member. Thehollow member and the machine may cooperate with each other by means ofa projection and recess with the cartridge being supported thereby onthe machine. The hollow member may be arranged, in use, to receive aprojection from a machine which may be arranged to at least partiallyextend into the cartridge and may extend along the cartridge. Theprojection may be arranged to restrict a bending moment exerted by theweight of the cartridge about the end region of the cartridge.

The cartridge may include an adaptor at one end. The adaptor may bearranged to be detachably mounted on the cartridge, for instance by afriction fit or by a bayonet fit. The adaptor may be hollow. The adaptormay include an outlet facing away from the cartridge having a greaterextent in one direction, transverse to the longitudinal axis of the tubethan an extent that is transverse to that direction which is alsotransverse to the elongate extent of the tube.

According to a further aspect of the present invention, a method ofbunching a supply of hollow film comprises causing relative movement ofa core and the hollow film such that part of the film surrounds the coreand then causing the film to be reduced in its elongate length to causemore film to surround the core.

The method may comprise loading hollow film having a greater internalcross-sectional area than the exterior cross-section of the cartridge.

The method may comprise loading film onto a core with the length of filmthat is so loaded being more than 10 or more than 20 or more than 50 orin the region of or more than 100 times the length of the core.

The method may comprise locating the open end of the hollow film ontothe core, for instance during the initial loading of the film. Themethod may comprise driving the film onto the core such as by a frictiondrive or, alternatively or additionally by a rotating member urging thefilm against the cartridge and along the cartridge which member mayrotate about an axis transverse to or perpendicular to the elongate axisof the film.

The method may comprise driving the film onto the core. The drive maycomprise a first drive causing film to move in a first direction alongthe cartridge and a second drive that moves the location at which thefirst drive acts in a second direction, opposed to the first direction.The first and second drives may act at the same time. The first drivemay comprise rotating at least a first member, and preferably twoopposed members which may be on opposed sides of the core.

The method may comprise removing the bunched up film from the core. Theremoved bunched up film may be used in a film cartridge as hereinreferred to or in a method of forming bags as herein referred to or inair bag manufacturing apparatus as herein referred to.

The core may comprise part of the cartridge.

The present invention also includes a cartridge which has been loaded bythe method herein referred to.

According to another aspect of the present invention, a packingcartridge comprises a cartridge having a supply of hollow film bunchedup along the elongate axis of the film located thereon, the film beingof greater length than the cartridge when the film is not bunched upalong the elongate axis of the film.

The film may be of greater cross-sectional area or circumference thanthe cross-sectional area or circumference of the cartridge.

The present invention also includes a cartridge when used in air bagmanufacturing apparatus as herein referred to or when used in a methodof manufacturing air bags as herein referred to.

The present invention includes any combination of the herein referred tofeatures or limitations.

The present invention can be carried into practice in various ways butseveral embodiments will now be described, by way of example, and withreference to the accompanying drawings in which:

FIG. 1 is a perspective view of a film cartridge 10;

FIG. 2 is a perspective view of the cartridge 10 in association withdrive rollers;

FIG. 3 is a schematic side view of the bag forming machine;

FIG. 4 is a perspective view showing a line of bags 12;

FIG. 5 is a front view of an alternative sealing station to which awafter board may be fitted;

FIGS. 6, 7 and 8 are a side and two plan views of different parts of thesealing station shown in FIG. 5;

FIG. 9 is a schematic perspective view of the sealing region of thesealing station shown in FIGS. 5 to 8 and

FIGS. 10 and 11 are a schematic perspective view from one end and aperspective view of the other end of the cartridge used with FIGS. 5 to9.

The cartridge 10 comprises a hollow cylinder 14 having enlarged enddiscs at either end. A tube of plastics film 18 is concertined orbunched up on the cylinder 14 with the film being retained on thecartridge by the end discs 16. With a full cartridge of 1 m in length,200 m of film may be concertined on the cartridge.

The cartridge is loaded onto the machine by the disc 16 at the rearwardend of the cartridge pushing a washer 20 against the reaction of aspring 22 to the right, when viewed in FIG. 3. The washer is mounted ona tube 24 over which the interior of the end of the cylinder 14 slides.With the washer 20 pushed back to be adjacent to a fixed back plate 26the forward disc 16 can be moved past the end 28 of an adaptor 30 untilthe round end of the adaptor is aligned with the forward end of thecylinder 14. The force exerted by the spring 22 then urges the cylinderover the round end of the adapter. Forwards movement of the cartridge isrestricted by abutment of an internal flange 32 of the cylinder, axiallyspaced from the end of the cartridge, with the axially facing end 28 ofthe adaptor.

The washer 20 is retained on the tube 24, when no cartridge is present,by engaging a small outwardly extending rim 34 at the end of the tube.

Removal of a cartridge is a reversal of the above described sequences.Loading and/or unloading may be effected automatically.

Any suitable alternative means of attaching or detaching the cartridgemay be provided. For instance, the forward end of the cartridge could beslid over the end of the adaptor, which may be a force fit or bayonetfit, with the rear end being dropped into or clicked into or retained ina suitable formation.

When a cartridge is in position, the forward end of the film is gatheredand pulled over the disc 16, to the right when viewed in FIG. 3. Thefilm is passed over the adaptor, past a first pair of rollers 36 andthen a second pair of rollers 38. The rollers 36 or 38 or both could belifted clear, either at the top or bottom or both to assist in passingthe film over the adaptor. Alternatively or additionally at least oneroller in one pair or at least one roller from each pair could be drivento assist in the passing of the film over the adaptor.

The film then passes over a work surface 40 and past a sealing station42. If desired, drive means could be provided downstream of the sealingstation to assist in the passage of the film past the sealing station.Alternatively or additionally air being blown through the film may causeor assist in causing the passage of the film through the sealingstation. Those drive means could comprise a pair of rotatable membersthat engage and urge the bags to the left when viewed in the drawings.Alternatively the drive means may comprise an operator urging or pullingthe film to the left.

With the film so loaded, the sealing station can be activated.

The sealing station comprises a pair of hot wires 44 that run across thewidth of the film. These are mounted on a pair of posts 46 mounted ateither side of the machine such that the wires can move down towards ananvil 48 beneath the film. A plate 50 on which the wires are mounted isurged downwardly by a cam drive which (not shown) is located beneath thefilm and to one side of the machine. In a revolution of the cam a rodconnected to the cam provides a positive drive to bring a plate 52, alsomounted on the posts 46, down towards the anvil by a greater distancethan the distance shown between the plate 50 and the anvil 48 and thenback again. The film at the sealing station can be stationary or movingwhen the seal is made. A compression spring 54 collapses towards thebottom of that movement to bias the hot wires against the anvil. In thelower position the hot wires form two spaced seals 58 across the film.At the same time a series of spikes 56 on the anvil form a series ofperforations 60 across the film between the seals 58, as shown in FIG.4.

The plate 50 is caused to return up, away from the anvil by brackets 62at each side that rest on top of the plate 62 and are connected to theplate 50 at their lower end. Thus, during compression of the spring theupper end of the bracket is able to remain stationary during the lowerpart of the downwards movement of the plate 52 but is caused to raisethe plate 50 when the plate 52 engages the upper end of the brackets 62again.

A fan 64 mounted to the right of the cartridge blows air down, throughthe cartridge in the direction shown by arrows 66. The air travelsthrough the circular right hand end of the hollow adaptor and thenthrough the lozenge 68 shaped part of the adaptor. The lozenge 68 alsoassists in spreading the film out.

In one embodiment (not shown) the cartridge is retained at its left handend, for instance by the disc 16 being held in a semi-circular recesssuch that it can not move to the left. Prior to that fitting, the nozzlecan be made fast with the left hand end of the nozzle within thecylinder of the cartridge with a bayonet fitting. This will assist inpreventing the cartridge from being urged into and jamming between therollers 36 and 38. The semi-circular recess may be able to be movedagainst a spring to allow the nozzle to be moved to the right and thensprung back towards the rollers. The semi-circular recess may abutagainst a stop to prevent the nozzle from being able to be jammedbetween the rollers. The tube 24 may extend further into the cartridgethan is shown in the drawings to provide extra support such as the solesupport for the cartridge. Alternatively, a tube may extend all of theway through the cartridge and the adapter may be attached to or beconnected to or integral with the tube.

At least one and preferably both of each of the rollers 36 and 38 may bedriven. The rollers 36 are arranged to drive the film at a slightlyslower speed than the rollers 38. This ensures that the film comes offthe cartridge with a small degree of tension in the extent between therollers. Some slippage of the film between the rollers and the adaptormay occur to allow for this differential drive.

In an alternative embodiment (not shown), the forward end of thecartridge is supported on a brush or between an upper and lower brushand the rollers 36 and 38 may be omitted. The brushes may provide orassist in providing support for the end of the cassette. The brushes mayalso provide a check on the ease at which the film can leave thecartridge. In this embodiment the film may be pulled through the sealingstation by an operator located downstream of the sealing station. Theoperator can pull as much or as little film past the sealing stationbefore effecting the next seal. In addition, by altering the angle ofthe extent of the plastic from the sealing station the volume of air inthe bag can be varied. For instance, if the film comes straight out ofthe station, in line with the axis of the tube, a relatively full bagcan be made. If that angle to the axis is increased by bending the bagabout to be formed then a less full bag is made. Other means may be usedto vary the amount of air in a given length of bag such as by anoperator squeezing the about to be formed bag.

With a seal being present at the end of the film, air from the fan tendsto force the walls of the tube of film apart upstream of the seal and inthe region of the work table 40 and downstream of the supply station, asthe film is advanced.

As the wires are brought down again, to form a further pair of seals,air is trapped in the bag between the newly formed seal and thepreceding seal. In place of the hot wires, the seal may be effected byapplying an impulse of heat, for instance to wires, and allowing thewires to cool whilst the film is trapped between the wires prior toadvancing the film.

A wafter board 70, which may be optional, is fast with the plate 50. Theboard 70 extends across the width of the film and extends downwardlyfrom a pivot mounting 72 towards the adaptor. Consequently, as the plate50 moves down, the board engage the film partially at an upstreamposition and then increasing downstream as it is caused to move aboutthe pivot (against the action of a spring, not shown) to waft airbetween the tube forwardly, past the sealing station, to ensure that thebag formed by the seal is or can if desired adequately filled.

It will be appreciated that the speed of the rollers can be adjusted tocontrol the rate of supply of the film to the sealing station.

It will also be appreciated that the frequency of seals being applied bythe sealing station can be altered.

Furthermore, the rate of supply of air can be altered, for instance byvarying the speed of the fan.

Any one or more of the air supply, length of film feed (regardless ofwhether this is manual or automatic such as by the rollers) roller speedor frequency of sealing can be controlled automatically for instance bya control (not shown). Furthermore the control can alter any one or moreof these factors to produce bags of a certain length for a predeterminednumber, and then bags of a different length or, alternatively oradditionally, bags of the same length having a different amount of airor alternatively or additionally bags of different lengths having thesame or a different amount of air.

In one mode, the operation of the sealing station may be effectedmanually, for instance by an operator operating a switch which may befoot operated, to cause seals to be effected by the sealing station.

It will be appreciated that, as the air is being supplied continuouslyfrom the air supply means, the space within the tube of film iscontinuously being filled with air and is not dependent upon a limitedsupply for each bag. It will also be appreciated that large bags can beprovided which, for instance, could be caused to be partially full toenable a bag to be bent around a corner.

An operator will be able to pack a customised product such as byproducing four tight small bags for the base of the product in a box,then four large but floppy bags for the lower corners which bags can bebent around the corners then, with the product being located in the box,two tight bags of intermediate length for each of the four sides, thenfour large but floppy bags for the upper four corners and finally twomedium sized, relatively loosely filled bags for the top. The bags canbe sequentially produced by a single operator as the product is beingpacked.

An operator may also be able to pack products on a work bench with bagsbeing supplied from the machine which is located to the side or beneaththe work bench. For instance, the bags could come up through an openingin the bench.

In order to load a cartridge with the tubular film, this could be doneautomatically. For instance, an end of a tube of film could be pulledover the cartridge to one end. Then driven rollers at that end regioncould rotate to drive more film onto the cartridge towards that one end.As the film bunches up onto the cartridge the rollers could be advancedfrom that one end towards the other end for instance by the axes of therollers being advanced by a caterpillar track mounting arrangement forthose rollers. For a 1 m length of cartridge, 50 or 100 m of film may beloaded on to it.

The embodiment shown in FIGS. 5 to 11 will now be described. It will beappreciated that the sealing station may be used in the embodimentpreviously described as may the cartridge. Furthermore, the embodimentmay be operated in the manner as previously described.

The sealing station 100 shown in FIGS. 5 to 8 includes a pair of spacedparallel wires that can be heated to form the spaced seals. The wiresare mounted on a static cross member 102. A slot (not shown) is providedbetween the wires into which the serrated blade 104 passes when piercingthe film to weaken the strip to allow detachment of the bags.

The seals are applied by actuating a first solenoid 106 andsimultaneously heating the wires. This causes spaced pads 108 to movedown and hold the film against the wires. At the same time that thewires are heated they are almost immediately turned off with the filmremaining held in place. After a predetermined time (during which thesealing temperature cools down to provide a good quality seal) a secondsolenoid 110 is actuated to lift the pads 108 and to permit the film tobe pulled forwards. Each solenoid is powered for an instant and yetstill the pressure of the pads is maintained for the required period.The action effected by the solenoids will now be described.

The pads 108 are mounted on a cross member 112 which is constrained tomove in a vertical direction only. A vertically reciprocatable drivenmember 114 is connected to the member 112 with guide rods 116 at eitherend with the members 112 and 114 being biased away from each other bycompression springs 118. In the position shown in FIG. 5, the member 114has been pushed down to compress the springs 118 to hold the filmagainst the wires.

To release the pressure of the pads and to move the pads upwardly thesecond solenoid is actuated to drive its plunger 120 to the right whenviewed in the figure. The plunger 120 is pivotally connected to a plate122. The other end of the plate 122 has a pin 124 extending therethroughwhich pin also extends through circular openings in spaced plates 126.The plates 126 are constrained to rotate about a fixed pivot 128. Thelower end of the plates 126 are pivotally connected to a link 130 whichis connected, at the other end, to the member 114 by a pivot 131. Aspring 132 extends from the pivot 130 upwardly to urge the pivot 131 inthat direction. In the position shown in solid lines, before thesolenoid 110 is activated, the spring 132 holds the link 122 in an overcentre position in which the lower pivot of the links 126 is below andslightly to the right of the fixed pivot 128, when viewed in FIG. 5.Although FIG. 5 does not shown this feature, nevertheless the,, pivot inpractice will be slightly to the right. This is known as an over centreposition.

When the solenoid 110 is activated the plates 126 rotate in a clockwisedirection. After only a small amount of movement the plates pass backover the centre with the spring 132 then urging the pivot 130 andtherefore the member 114 upwardly, first to relieve the pressure of thepads on the film and then to raise the pads clear of the film, when thesprings 118 have urged the members 114 and 132 apart to their permittedmaximum. In this position, the plate 122 is in the position shown indashed lines in FIG. 5.

To apply the seal the solenoid 106 is activated to move its plunger 134to the left, when viewing FIG. 5. The plunger is pivotally connected toa plate 136 with the pin 124 being pivotally connected to the plate 136at the other end. Consequently this movement urges the plates 126 in ananticlockwise direction to move the plates 126 to the position shown insolid lines in FIG. 5. This first of all moves the pads down to contactthe film and then urge the pads more firmly against the film as thesprings 118 are caused to be compressed.

Whilst the plate 126 is able to rotate only in relation to the pin 128,the pin 124 is able to move both rotationally and translationally withrespect to the plate 122 by sliding in a slot 138 of that plate.Consequently, in the position shown in solid lines, the pin is to theright of that slot and all movement of the solenoid 110 is instantlyapplied to the plate 122. Once the plunger 128 has pulled the plate 122,such that the pin 124 is at the left hand end of the slot, the solenoid110 imparts sufficient force to “unlatch” the over centre action of theplates 126. This allows the spring 132 to return the member 114 andconnected parts upwards.

As each solenoid only effect a “short” sharp movement and are thereafterturned off, the solenoids can be relatively low in power consumption andrelatively inexpensive.

As shown in FIGS. 10 and 11, the film 140 is bunched up as previouslydescribed. In this arrangement though there is nothing in the interiorof the film. The compacted film is largely self supporting and isunattached within an elongate cardboard container 142. The container 142may be square in cross section and is arranged to be mounted with onecorner above another on one or more V-supports 144 which may be spacedfrom each other. The front end of the container 142 includes ahorizontal slit 146 extending almost from one corner to the other of thecontainer. The other end of the container includes an opening. In use,the container is simply dropped onto the supports 144 with the slitfacing the sealing station and the other end of the container beingagainst a plate having an opening through which air may be blown intothe container and through the tube. In this embodiment, the film may bearranged to be manually pulled from beyond the sealing station withoutthere necessarily being any drive rollers.

The air that is blown through the tube passes the sealing station toinflate the tube between the sealing station and the seal on the tubedownstream of the sealing station. Any length of bag can be formedsimply by pulling the required length of tube past the sealing stationbefore effecting the next seal. Similarly the bags can have any desiredvolume of air such as by pulling the tube slowly past the sealingstation or keeping the tube stationary after pulling, to allow more airper unit cross section, or pulling the tube quickly, or immediatelyeffecting the seal after pulling to allow less air in. Alternatively oradditionally the tube can be pulled upwardly or downwardly out of thesealing station to allow less air in.

A pair of rotatable pinch rollers 150 shown in FIG. 9 may be providedjust before the sealing station or just after or both. These may helpthe tube to remain spread out across the width of the sealing station.The may also prevent an operator from being able to inadvertently gettheir fingers caught in the sealing station. Furthermore, the upstreamrollers 150 are abutted by a spreader plate 152 around which the film isspread to prevent the plate 152 from reaching the sealing station. Theplate 152 has a recessed front edge 154 which allows the air to flowpast that plate within the tube. Any or all of the rollers may becastillated along their length to provide a varying outside diameteralong the axial length whereby the air may more easily flow through toassist in the inflation of the tube.

Attention is directed to all papers and documents which are filedconcurrently with or previous to this specification in connection withthis application and which are open to public inspection with thisspecification, and the contents of all such papers and documents areincorporated herein by reference.

All of the features disclosed in this specification (including anyaccompanying claims, abstract and drawings), and/or all of the steps ofany method or process so disclosed, may be combined in any combination,except combinations where at least some of such features and/or stepsare mutually exclusive.

Each feature disclosed in this specification (including any accompanyingclaims, abstract and drawings) may be replaced by alternative featuresserving the same, equivalent or similar purpose, unless expressly statedotherwise. Thus, unless expressly stated otherwise, each featuredisclosed is one example only of a generic series of equivalent orsimilar features.

The invention is not restricted to the details of the foregoingembodiment(s). The invention extends to any novel one, or any novelcombination, of the features disclosed in this specification (includingany accompanying claims, abstract and drawings), or to any novel one, orany novel combination, of the steps of any method or process sodisclosed.

1-88. (canceled)
 89. Airbag manufacturing apparatus comprising a tube offilm and a sealing station, said tube of film being arranged to be fedto said sealing station which station, in use, is arranged to applyseals across the width of a tube to trap air in the tube between twospaced seals, with air being arranged to be supplied to be trappedbetween two spaced seals through the tube, from an open end of the tube,characterised in that the tube is arranged to be bunched up in the axialextent of the tube.
 90. Apparatus as claimed in claim 89 including asupply station in which the tube is arranged to be supplied to thesealing station from the supply station with the supply station beingarranged to maintain a passage through the tube.
 91. Apparatus asclaimed in claim 89 in which the air that is arranged to be trappedbetween two spaced seals is arranged to pass through the interior wallof the tube with the rube having nothing in it along its bunched uplength.
 92. Apparatus as claimed in claim 90 in which the supply stationincludes a hollow member around which the tube is located.
 93. Apparatusas claimed in claim 92 in which air that is arranged to be trappedbetween two spaced seals is arranged to pass through the interior of thehollow member.
 94. Apparatus as claimed in claim 89 in which the airthat is arranged to be trapped between two spaced seals is arranged topass through the interior of the tube over the exposed interior wall ofthe tube.
 95. Apparatus as claimed in claim 89 in which the bunched uptube is arranged to maintain an opening throughout its length bymaintaining such an opening solely as a result of compression inducedduring bunching of the tube.
 96. Apparatus as claimed in claim 90 inwhich the supply station is removably mounted on the apparatus. 97.Apparatus as claimed in claim 89 in which the tube of the film isarranged to pass over a spreader having a greater extent in thedirection across the tube in the direction that a seal is arranged to bemade by the sealing station than in a direction transverse thereto. 98.Apparatus as claimed in claim 89 in which the frequency of the operationof the sealing station is adjustable.
 99. Apparatus as claimed in claim89 in which the rate of feed of the tube past the sealing station isadjustable.
 100. Apparatus as claimed in claim 89 in which the air thatis arranged to be trapped between two spaced seals of the tube issupplied by a fan.
 101. A method of forming bags containing aircomprising supplying air to a tube from which the bags are formed fromone end of the tube, through the tube, and past a sealing station andeffecting a seal across the tube by the sealing station, characterisedin that the method further comprises passing air through the tube withthe tube having been bunched up in the axial extent of the tube.
 102. Amethod as claimed in claim 101 comprising passing the tube over aspreader when loading the machine with the tube and supporting thespreader with the tube.
 103. A method as claimed in claim 101 comprisingvarying the amount of air in a given length of bag.
 104. A cartridgeincluding a tube of film when the tube of film is used in the apparatusof claim
 89. 105. A cartridge arranged, in use, to be made into air bagscomprising an elongate tube from which air bags are to be made, the tubeincluding a passage throughout the length thereof through which, in use,air is arranged to pass in order to comprise the air in the air bags,characterised in that the tube has been bunched up along its elongateaxis such that the length of the bunched up film is less than the lengthof the extended film.
 106. A cartridge as claimed in claim 105 in whichthe film is detached from at least one end of a container of the tube.107. A cartridge as claimed in claim 105 including an elongate memberextending through the tube through which member air is arranged to flow.108. Use of a cartridge comprising an elongate tube that is bunched upalong its elongate axis in the manufacture of air bags comprisingpassing air through the tube in order to comprise the air in the airbags.